US Patent 12021506 Bulk acoustic wave resonators with patterned mass loading layers

Aspects of this disclosure relate to bulk acoustic wave resonators with patterned mass loading layers. Two different bulk acoustic wave resonators of an acoustic wave filter and/or an acoustic wave die have respective patterned mass loading layers with different densities. The patterned mass loading layers contribute to the two different bulk acoustic wave resonators having different respective resonant frequencies. Related bulk acoustic wave devices, filters, acoustic wave dies, radio frequency modules, wireless communication devices, and methods are disclosed.